This invention relates to apparatus for maintaining a solar collector in a desired or optimum attitude with respect to the sun.
Many solar energy collecting devices work most efficiently when positioned generally upwardly, perpendicular to the rays of the sun. Because the position of the sun varies both daily and seasonally, various prior art devices have been used to position the collector, ranging from manual adjustment, clockwork adjustment, photoelectric sensors, and combinations of the above. For example, U.S. Pat. No. 3,177,367 would use side-mounted photocells to control the amount of illumination behind a set of louvers. U.S. Pat. No. 3,370,293 would have a planar array of sensors located either within or without a cylinder and optionally movable with respect to the cylinder for use in a direction finder; U.S. Pat. No. 3,311,748 employs a movable light refracting slot in an instrument for determining the position of the sun. U.S. Pat. No. 3,423,589 has paired photocells to trace patterns; U.S. Pat. No. 3,478,219 has a pyramidal optical prism and multiple photocells to provide both fine and coarse tracking of the sun; U.S. Pat. No. 3,200,905 utilizes multiple rings of detectors having varying field of view in tracking devices; U.S. Pat. No. 3,739,247 has photocells and a reference pattern to set and article in a predetermined planar position; U.S. Pat. No. 3,917,942 uses a fixed photocell quadrant sensor for controlling the position of louvers; U.S. Pat. No. 4,031,385 teaches a clock-driven override system in combination with a photovoltaic suntracker to compensate for periods of partial cloud cover; U.S. Pat. No. 4,041,307 would use a combination of a lens-photocell system and a shadow photocell system for fine and coarse tracking of the sun; and U.S. Pat. No. 4,103,151 uses photocells spaced around the periphery of a solar collector for the aiming of that collector.
The prior art does not teach a simple photoelectric sun tracker, which will track the sun accurately, to begin acquisition when the solar collector is more than 90.degree. from its desired position, and not be fooled into falsely tracking the edge of a cloud passing over the sun.